In the field of solid-state lighting devices, e.g. LED modules, various solutions are known employing flexible support structures.
We may mention for instance the products sold under the trade mark Osram Linear Flex by companies of the Applicants' corporation, or the product sold under the trade mark Matrix Platform by Philips Lumileds. These are linearly shaped modules wherein the presence of a flexible substrate offers a good level of flexibility both in design and application. The assembly may be implemented, for example, by applying an adhesive material on the back side of the device.
From the range of products of SeeLuce (Korea) LED modules are known which are very thin and lightweight, and which exhibit high flexibility. The product is available in various shapes and may be used, for example, for indoor lighting, general lighting applications and architectural lighting. In the production of the company CoolEdge Lighting Inc., Richmond (Canada), LED modules are known having the shape of linear or square sheets.
Such products may be considered as generally conventional solutions from the point of view of design, and are destined mainly to linear applications. Their flexibility, actually, enables to broaden the application field to curved or rounded surfaces. Moreover, beside their flexibility, they have on the whole conventional features in their structure, also as far as the optical appearance is concerned. This also true in the case of support members including square or possibly circular shaped sheets, which enable to widen the possible application range. In this case, too, although they exhibit flexibility and good form factor characteristics, these products do not offer outstanding features as regards design, even when particularly thin substrates are used (e.g. 50 μm thin) and/or the base materials include resins such as PET or PI.
Various solutions may include, as a cover material, a so-called solder mask material. These are generally acrylic materials which however limit the support reflectivity. This feature may be a disadvantage e.g. in indoor lighting, where high efficiencies are desirable.
Beside flexibility, another feature common to these conventional products is that the light emission distribution is basically equal to the distribution of light sources. This is a limiting factor in some applications (for example in architectural lighting). However, in other applications such as indoor lighting (offices, shops, industrial hangars, etc.) the light radiation distribution may have to meet needs that the light radiation source in itself is unable to fulfil. In this case, the shaping of light radiation distribution may be achieved through the luminaire, e.g. via secondary optics included in the luminaire itself.
Such lighting devices may include three or more components, e.g. a (metal) body, a light engine and diffusers/secondary optics adapted to shape the light radiation emitted by the light engine.
The need is therefore felt to provide lighting devices adapted to employ electrically-powered solid-state light radiation sources, e.g. LED sources, which may allow for a broad range of optical configurations, without involving a complex structure and/or manufacturing method. Moreover, the need is felt to achieve high reflectivity in the light engine support member, and therefore a high lighting efficiency.